The present invention related to a surveying instrument, and more particularly to an aid apparatus for level surveying instrument.
In civil engineering, there are two instruments for surveying the horizontal level of two positions: the leveling rod and the leveling pipe. The leveling rod is for surveying the horizontal level of a short distance, and the leveling pipe is for surveying the horizontal level of a long distance.
The conventional leveling pipe had a soft tube receiving color liquid therein. Two ends of the soft tube are closed by two covers for preventing the color liquid escaping. In operating, user has to turn the covers loose first for air flowing between outside and the soft tube. The surfaces of the color liquid at two ends of the soft tube are position at the same horizontal level caused by the atmospheric pressure. Positioning two ends of the soft tube at two positions, user can identify the horizontal level according to the surfaces of the color liquid at two ends of the soft tube.
To store the conventional leveling pipe, user usually wound the soft tube to decrease the size thereof. Next time, when use the leveling pipe again, user will find air bubbles in the color liquid. These air bubbles will affect the accuracy of the leveling pipe in precise survey. So, user must squeeze the tube for getting the air bubbles out of the color liquid before surveying.
According to the objective of the present invention, an aid apparatus for level surveying instrument comprises a housing having a receiving chamber therein, a channel at one end of the receiving chamber, a window at one side of the receiving chamber, and a socket opening at the side wall of the housing connecting to the channel. A controlling member is slidable received in the housing. The controlling member has at least one seal block to seal the channel for isolating the receiving chamber from the socket opening, and a driving member is provided at the housing for driving the controlling to shift, whereby the sealing block being driven by the driving member to seal the channel and to depart from the channel to prevent bubbles formed in color liquid.